Although there are no securities exchanges in Texas, 4,252 broker-dealers organizations conduct securities transactions, with the number of employees at 30,977. Securities investment advice is professionally marketed by 581 registered firms. Texas is the headquarters of 341 NASDAQ companies, 24 NASDAQ market makers, 71 AMEX companies (almost 11% of the national total); and the state has incorporated 53 NYSE-listed corporations. The top five in terms of revenues are: Electronic Data Systems Corp., TXU Corp., Reliant Energy Corp., Southwest Airlines Corp., and Allied Waste Industries, Inc. The State Securities Board, established in 1957, oversees the issuance and sale of stocks and bonds in Texas.